title: Influence of bone morphogenetic protein-2 on the extracellular matrix, material properties, and gene expression of long-term articular chondrocyte cultures: loss of chondrocyte stability.
abstract: The aim of this study was to determine the effects of bone morphogenetic protein-2 (BMP-2) on articular chondrocyte tissues grown as monolayers in vitro for up to 8 weeks. Articular chondrocytes were isolated from New Zealand White rabbits and plated in monolayer cultures. The cultures were supplemented with 100 ng/mL of BMP-2 for up to 8 weeks and the extracellular matrix (ECM) composition, material properties, and messenger RNA (mRNA) expression were analyzed. mRNA expression of cartilage-specific genes, type II collagen, and aggrecan showed that BMP-2 enhanced chondrocyte stability for up to 3 weeks. After 3 weeks in culture, there was substantially more type I collagen expression and more osteopontin and runt-related transcription factor 2 expression in 5- and 8-week cultures treated with BMP-2 than in controls. Additionally, matrix metalloproteinase-13 and ADAMTS-5 (A disintegrin-like and metalloproteinase with thrombospondin 5) were upregulated in 5- and 8-week cultures treated with BMP-2, coinciding with a loss of ECM density, collagen, and proteoglycan. Eight-week tissue stimulated with BMP-2 was more fragile and tore more easily when removed from the culture dish as compared to controls, suggesting temporal limitations to the effectiveness of BMP-2 in monolayer systems and perhaps other models to enhance the generation of a cartilage-like tissue for tissue engineering purposes.
authors.affiliation: Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Krawczak
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Westendorf
authors.forename: Cathy S
authors.initials: CS
authors.lastname: Carlson
authors.forename: Jack L
authors.initials: JL
authors.lastname: Lewis
mesh_terms: D053674:Aggrecans / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001696:Biomechanical Phenomena / Q000187:drug effects; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D002358:Cartilage, Articular / Q000166:cytology*; D002452:Cell Count; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D020219:Chondrogenesis / Q000187:drug effects; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D005109:Extracellular Matrix / Q000187:drug effects* / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D053509:Matrix Metalloproteinase 13 / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011817:Rabbits; D044967:Serum; D013997:Time Factors
chemical_list: D053674:Aggrecans; D055396:Bone Morphogenetic Protein 2; D024042:Collagen Type I; D024043:Collagen Type II; D053509:Matrix Metalloproteinase 13